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I gnitrh-ltatrs attent @Hirt JAMES B. BEAN, or `BLTIMORE, ivIARYLAND2 AssIcNon r10 HIMSELF AND va. H. BALDERsTo-N, or sAME'PLAcE;

Laten Paare No. 69,614 dates 00am 8,1867.

lMom: or coNs'rRUcrING Montos roectsrmc ALUMINUM PLATES roe ARrIrioIAL rreru'.

TO ALL WHOM IT MAY CONCERN:

Be it kncwnthat I, JAMES B. BEAN, of the city and county of Baltimore, and State ofMaryland, have invented a new and improved Method of Constructing Moulds for Casting Aluminum Plates for ArtifioialTeeth;

-and I do hereby declare the follovring to be a full, clear, and exact description of the same, sndicient to enable one skilled in the art to which the invention appertains tc make use of it, reference being had to the accompanying drawings,rforming part ofV this specification, in Which- Figure 1 represents a top view of the impression-cup C. l

Figure 2 shows theV upper side'of lthe model D.

Figure 3 is a top view of the mould B.

Figure 4 is a bottom viewrof the same, a'nd Figure 5 is aview'of .the concave side of the matrix. l

In ,this invention the contractibility of thev aluminum, or other metal used for casting the plates, is compensated by `the enlargement of thej moulds in which the plates are cast, a new composition beingused for the mould, andanew series of operations employed in its construction for the purpose of obtaining the end desired.

The advantages which would result from the use of aluminumgplates as a base for artilicial teeth have long been acknowledged by every one acquainted with the subject, vand many efforts have been made to utilize the metal for this purpose, and although the casting of the metal has long since been attained by myself, as well as oth'ers,"iu moulds of the dimensions ofthe patients mouth,yet the plate, when cooled, will be so much smaller as to `beentirely unfit for the purpose. This diiicnlty, hitherto deemed insuperable, can' be entirely overcome 'by a nevv process, which I have invented, vand which I shall now proceed to describe in detail. Y

In the/first place, I take an impression of the patients mouth in' plaster of Paris, either in a thin elastic metallic impression-cup, or in the usual way. I deem the thin elasticmetalflic impressio'ncup C far preferable for the purpose, andAzI use one of thin sheet brass, struck4 up between dies, so as to' make an approximate tit to the patients mouth. This cup or plate is coated on its upper surface with a thin coating of gum-shellac. While warmed over slamp, Src., to the melting pointof the shellac, the whole is quickly enveloped in a handful of cotton, which is pressed upon it until cool, when the superfluous ,cotton is removed, thus leaving a coating oti adherent fibre, whichwill ed'ectually'retain the thin film of plaster used for the impression, which is now taken in the usual manner, using, hovvever, much less plaster-'than by theV ordinary impression-cup. The elasticity of this cup allows the plaster to expand freely, and moreover is easily removed from the impression, when desired, by heatingit tothe melting point of the shellac. Secondly, intothis impressionjust taken, after being'varnished, &c., as usual, I cast a model, D, of plaster of Paris.V l v Thirdly, upon this model', after being varnished, Src., I formfavmould, B, in several parts, composed'of the v7best calcined plaster of Paris. i The drawings show a mouldfconstructed inpmy laboratory in making a set of artiticialteeth, which gave perfect satisfaction, in which six pieces are used, three, b bl b, forming the sides Vor walls, and three, b b* Z55, forming thebottom of the mouldall being of the shape shown in iig. and each {itting into the other by short dowels or projections and recesses on their contiguous surfaces. The pieces thus, fitted to each other may lbe held together by a' band of India rubber, or any other suitable fastening.

'Fourthly, in'to this mould, after being varnished, dto., I cast a compound of'two parts, by weight, of' powdered pumice-stone, and fone part of plaster o t Paris, mixed with waterf" I first boil the powdered pumice in water fora moment to `eicpel the air, then wash and cool, and afterwards add the plaster. The composition having become solid, the parts of the mould are removed 've-ry carefully oneat a time to prevent injury to the fragile cast. This cast is thematrix on which thel perfect-fitting plate ispioduced. and lforms aapart of the mould in which the aluminum is tolbe cast.

`'The object to b e attained by the foregoing operations is accomplished in the following manner:

From carefulexperiments and delicate micrometer measurements it is fonndithat a east-aluminum plate,

two anda half inchesiin width, in beingheated from the ordinary temperature of the mouth to near the melting point of the metal, expands two hundred and ft'y ten thousan'dths of an inch. An impression in plaster` of an equal width, in a thin elastic impression-cup, expands, in setting, fifty-five ten theusandths in the saine distance. A. plaster model east into this impression expands eighty-three ten thousandths. The mould formed on this model expands eighty-three ten thonsandths. The compound of pumice-stone andpl-.ister east into this mould expands seventy-five ten thonsandths in setting. Expansion of the impression, .0055 of an inch; expansion of the first cast, .0083 of' an inch; expansion of the plaster mould, .0083 of an inch; expansion of' the matrix. 0075:.0290. The contraction of the aluminum plate may he put down at two hundred and sixty ten thonsandths in cooling, from its point of cengelation to the temperature of the mouth. Then the contraction ol" the mould in drying may he safely put down at sixteen ten thousandths. lhen .0260 -l.0010::.027011thc vwhole sum of contractions, .0296-.0276:.0020. This gives a plate two one thousandths of an inch larger than the gums from which the impression was taken, which is necessary to a comfortable fit. These measureients, determined before the actual experiment with a dental plate was tried, are found to work out exactly in practice, and the result is a most perfectditting plate, adheringl more perfectly tothe gums hy atmospheric pressure than any other heretofore produced.

In order to comple-te the mould for casting the plate for a set of teeth the model or patternplate of wax, er wax and tin-foil, is gotten up as if for a cast ol` vuleanite work, except the plate is one-haiiI the thickness usually employed for vulcanite, the teeth or blocks having their pins embedded in plaster, and trimmed smooth, so as to ferm the groove in the plate along the line ofthe teeth for the purpose of fastening the teeth thereto, and also to enable them to be easily separated from the wax. The teeth or blocks are now oiled all over their surface, and put in their proper place on the wax model, in the articulator, if necessary, and hot melted wax is introduced under and around each tooth and block, so as to till up all the vacancies between and beneath the teeth or blocks. The wax is also carefully modelled to represent all the fullness and outline desired in the aluminum plate. The plate and teeth are new placed upon the matrix, and the edges secured all around hy melted wax, and the whole made as smooth as possible. The teeth are now carefully removed from the wax plate, being careful that no wax comes away with them. New cut out the groove, into which the pins et' the teeth er hleeks project, all along the line of the teeth; again replace the teeth, and repair any damage to the wax fitting against them. This matrix, containing the pattern-plate and teeth, is now secured in the lower half of the flask hy means of the composition 0f two parts of pumiee-stone and one of' plaster, mixed with water in the same manner as if for a ease of vuleanite work. The teeth are new removed, and the whole surface of the wax and composition is oiled. The upper portion of' the flask is then put on and filled in like manner, making provision for the gate and bents. When solid the flask is warmed, opened, and thewrax patternplate removed, leaving the desired mould for the aluminum plate.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

l. I elai-m the thin metallic impression-cup C, for the purpose specified.

2. I claim the use of the model B, made in several pieces, substantially as and for the purpose described.

3. I claim the process of constructing moulds for casting aluminum plates for artificial teeth, substantially as above described.

JAS. B. BEAN.

Witnesses:

.Linus H. GnIDLnr, SOLOAQC. KEMoN. 

